Most restaurants, especially fast food restaurants, use commercial deep frying units to cook food items such as, for example, french fries, chicken, or fish by submersing the food items in hot cooking oil. The cooking oil (typically vegetable oil) has a limited shelf life, as it degrades and becomes contaminated by pieces of food as well as water and fats released from food during the cooking process. As a result, the cooking oil is changed on a regular basis.
Waste cooking oil can pose a pollution hazard if not handled properly. To prevent pollution of waterways and clogging of private and municipal drain systems, restaurants and other food preparation facilities typically save used cooking oil and employ sewage traps to filter grease out of waste water streams. Renderers collect the waste cooking oil, and then use it in products such as animal feed or biodiesel fuel. Yellow and brown grease (also commonly referred to as trap grease, sewage grease, or black grease) are two forms of waste cooking oil that are readily available in bulk quantities. Yellow grease is of a slightly higher quality than brown grease and typically has a free fatty acid (FFA) content of between about 4 and 15 weight percent, while brown grease typically has a FFA content of up to about 60 weight percent. The current supply of yellow and brown grease exceeds the demand for these feedstocks.
Given the ample supply of waste cooking oil and the relatively limited number of products currently being produced from collected waste cooking oil, there is a need for new products derived from waste cooking oil.